Laser Components has announced the availability of a range of holographic wire grid polarisers from Optometrics USA. The fabrication process for the devices incorporates multiple infrared materials, and their performance is further optimised through careful choice of over-coatings where appropriate.
Calcium fluoride (CaF2) and barium fluoride (BaF2) have low refractive index (high Tx) values and do not require anti-reflective (AR) coatings. Zinc selenide (ZnSe) has a high refractive index and transmission at specific wavelength regions that which can be enhanced by an AR coating on the rear surface only. Laser Components explains that ZnSe is usually optimised for transmission at specific laser lines, typically from 9 to 11µm. KRS-5 is not normally AR coated as this would restrict its broad transmission range, which is its primary advantage. Germanium (Ge) is AR/AR coated to maximise transmission at 10.6µm